When we swim, the water removes the heat out of our body. We can also say that our body tend to equilibrate with the temperature of the water. When the swimmer get out of the water, the remaining water in the body tend equilibrate its temperature with the air. The consequence is that, the water in our body will absorb some heat from the swimmer's body thus making himself very cold.

We can simply state it as: the evaporation of the water in the skin of the swimmer take some of the heat from the body thus cooling it (the body) at the same time.

▲ Swimming is a very activity for burning fats but many times swimmer feels cool after getting out of the pool after a enjoyable swimming experience

pool is full of water and water is a very good absorber of heat, while swimming water absorbs the heat present in our body, so, to keep balance between the drowning tempreture our body releases a plenty of heat.

Due to which we feel weak and cold as most of the heat present in our body has been absorbed.

another reason can be of latent heat of vapourization. due to this water present on our body after getting out of the pool evaporates by taking up the heat generated by our body.

It can be seen many times when after bath our body gets dry on itself, here it is the only water who absorbs heat of our body to get evaporated and gets dissappeared.